Low adhesion surface coatings comprising imides or amides of fluorene succinic acid (9)

ABSTRACT

Compositions for forming low adhesion surface coatings on cellulose-containing materials wherein the main coating agent is an imide or amide of fluorene succinic acid-(9) substituted on the nitrogen with aliphatic or cycloaliphatic radicals of five to 22 carbon atoms and the coated cellulose containing materials which are useful in pressure-sensitive adhesive tapes.

I United States Patent 1111 3,619,225

[72] Inventors Hans-Werner Demmig; [51] Int. Cl 4 1 4 t v C07g 17/00 Kurt Rehnelt, both of Dusseldorf, Germany [50] Field of Search 1. r 260/558 A. [2]] Appl. No. 13,169 326 D; 106/287; 117/144 22] Filed Feb. 20, 1970 i451 Patented Nov. 9, 1971 [561 References (31M [73] Assignee Henkel & Cle., G.m.b.1l. UNITED STATES PATENTS Dusseldorf-Halthausen, Germany 3.538.054 11/1970 Demmig et 31v 1 260/849 x [32] Priority Mar. 15,1967 OTHER REFERENCES {3 Chemical Abstract v01. 59:7882C. I963 Continuation-impart of application Ser. No. Primary Examiner- Morris Liebman 712,380, Mar. 12, 1968, now Patent No. Assistant Examiner-T. Morris 3,538,054. Attorney-Hammond & Littell [54] Low ADHESION SURFACE COATINGS AllSflRACT: CIFTPOSlIlOH'S fQI fon'ningnlfw ildhesionhsurface COMPRISING IMIDES 0R AMIDES 0F FLUORENE COdllllgS on ce u ose-contalnmg matena s w erem t e mom SUCCINIC ACID (9) coatlng agent 15 an 1m1de or am de ol: fluorene succmlc and- Cl N D (9) substituted on the nitrogen wlth allphatlc or cycloallphatlc 5 0 rawmgs radlcals of five to 22 carbon atoms and the coated cellulose [52] U.S. Cl 106/287, containing materials which are useful in pressure-sensitive adhesive tapes LOW ADHESION SURFACE COATINGS COMPRISING IMIDES OR AMIDES OF FLUORENE SUCCINIC ACID (9) PRIOR APPLICATION PRIOR ART Surface coatings of cellulose-containing tapes having a The said amides or imides of fluorene succinic acid-( 9) may be used as such to form the coatings on cellulose-containing materials, but are preferably added in small amounts to coating compositions having a modified melamine resin base. Examples of suitable melamine resins are those formed by condensing one mole of melamine with 4 to 7 moles of formaldehyde and 0.5 to 1.5 moles of urea and modifying the resulting resin with l to 2 moles of polyol such as ethyleneglycol, diethylene glycol, trimethylol propane, etc. Also, up to one- 0 third of the said resin may be replaced by a melamine resin lower adhesion than that of pressure sensitive adhesives are useful for coating the reverse sides of adhesive tapes, particularly when sold in rolls. The said coatings have to be effective in relatively small amounts, should not diffuse into the adhesive and should be capable of being easily bonded to the base material. German Pat. No. 969,597 discloses low adhesion surface coatings prepared from polymers of vinyl esters of higher fatty acids of not more than 16 carbon atoms. However, these coatings have a relatively low affinity for cellulose and are apt to become separated from the base material and diffuse into the adhesive itself. Organic polyisocyanurates have been added thereto to eliminate these disadvantages but the use of organic polyisocyanurates has considerable disadvantages in processing due to their moisture sensitivity and possible toxic properties.

OBJECTS OF THE INVENTION It is an object of the invention to provide novel compositions for forming low adhesion coatings on cellulosecontaining material which will firmly adhere thereto.

It is another object of the invention to provide novel low adhesion coated cellulose-containing materials useful as a base for pressure sensitive adhesive types.

These and other objects and advantages of the invention will become obvious from the following detailed description.

THE INVENTION The novel coating compositions of the invention are compositions containing at least one compound selected from the group consisting of imides and amides of fluorene succinic acid(9) having at least one nitrogen substituent selected from the group consisting of aliphatic and cycloaliphatic of five to 22 carbon atoms. The said coating compositions usually contain an inert organic solvent or water for easy application.

The imides or amides of fluorene succinic acid( 9) may be prepared by the usual methods of producing them such as by reaction of the free acid, its anhydride or halide with the appropriate amine. Fluorene succinic acid-(9) may be prepared by reaction of maleic acid anhydride and fluorene as described in Chemische Berichte, Vol. 95, 1962, p. 3017.

For the preparation of the imides, the said acid derivative and a primary amine may be reacted in substantially equimolar amounts in a molten form for 3 to 12 hours at a temperature of 120 to 250 C. The amides may be formed by the same process using a primary or secondary amine with at least 2 moles of amine per mole of acid. Solvents may also be used, particularly in the preparation of the amides. Examples of suitable inert organic solvents are toluene, xylene, cumeme, cymeme, tetrahydronaphthalene, methyl naphthalene, etc.

Examples of suitable amines for the preparation of the amides and imides are aliphatic and cycloaliphatic amines having five to 22 carbon atoms, such as cyclopentylamine; cyclohexylamine; N-lower alkyl cyclopentylamines and cyclohexylamines; pentylamine; hexylamine; isomers of decylamine, dodecylamine, tetradccylamine, hexadecylamine, octadecylamine and docosylamine; dialkyl amines such as dibutylamine, N-methyl octadecylamine; mixtures of amines derived from natural fatty acids, etc. Amines having a terminal primary amine grouping are preferred. I

The said imides and amides of fluorenesuccinic acid-( 9) are usually solids and may be purified by recrystallization from alkanols such as ethanol, isopropanol, etc., or hydrocarbons such as toluene, xylene, etc. or ethers such as dioxane.

etherifled with a lower alkyl' monoalcohol. Preferably, the coating agent contains about 0.5 to 10 parts by weight of the imide or amide of fluorene succinic acid per 100 parts by weight of the melamine resin.

The compositions of the invention can be utilized as such for the preparation of surface coatings, or they can be dispersed in water. The solutions or dispersions in water can be applied in well-known manner onto cellulose-containing base materials. For example, the application may be effected by rolling on, painting on, brushing on or spraying on. If so desired, the water or the solvent may then be evaporated, for example by heating the temperatures of about -150 C. The amount of the adhesive repelling composition to be applied is preferably between 10 to gm./m. preferably 20 to 50 gm./m. of cellulose material.

The surface coatings of the invention are distinguished by their glossy appearance, and in contrast to silicone films, they can be written upon such as with a ball point pen. The coated papers usually have a higher resistance against tearing due to the coating. Because of the strong adhesion of the coatings, in particular to paper, no diffusion into the pressure sensitive adhesive occurs when the coated paper is rolled. The low adhesion surface coatings of the invention are particularly useful for coating of the reverse sides of pressure-sensitive adhesive tapes of paper and cellulose hydrate foils.

1n the following examples, there are described several preferred embodiments to illustrate the invention. However, it should be understood that the invention is not intended to be limited to the specific embodiments.

EXAMPLE I 264 gm.(l mole) of fluorene succinic acid anhydride and 1 mole of octadecylamine were reacted together for 5 hours at 200 C. in a l-liter glass flask equipped with an air cooler and a stirrer. The reaction was completed after this time and the solid contents of the flask were poured out and pulverized. The raw product was recrystallized from a 1:1 mixture of toluene and methanol to obtain N-octadecyl-fluorene succinimide having a melting point of 84 C. and a nitrogen analysis of2.80 percent (2.71 percent theoretical).

Using the same procedure except for the use of hexadecylamine and tetradecylamine, there was obtained, respectively, N-hexadecyl-fluorene succinimide, 11, having a melting point of 78 C. and a nitrogen analysis of 2.74 percent (2.87 percent theoretical) and N-tetradecyl-fluorene succinimide, Ill, having a melting point of 74 C. and a nitrogen analysis of 3.01 percent (3.05 percent theoretical).

EXAMPLE II 52.8 gm. of fluorene succinic acid anhydride and 96 gm. of hexadecylamine in 1 liter of toluene were refluxed in a 2 liter glass flask provided with a stirrer and an air cooler. The solvent was then distilled off and the raw product was recyrstallized from a 1:1 mixture of xylene and toluene to obtain N,N'- dihexadecyl-fluorene succinic acid amide having a melting point of 143 C. and a nitrogen analysis of 4.10 percent (theoretical-3.86 percent).

EXAMPLE lll A mixture of 2.45 kg. of melamine, 1.6 kg. of formalin (30 percent), 0.78 kg. of urea, 1.85 kg. of paraformaldehyde, 1.25 kg. of ethylene glycol and 1 kg. of water were heated together at 80 and a pH of 8.5 until a precipitation number of 5 was attained after which the mixture was rapidly cooled to room temperature to obtain a melamine-urea resin.

EXAMPLE 1V EXAMPLE V 80 mg. of the melamine-urea resin of example 111 and 20 gm. of the etherified melamine condensate of example IV were admixed with 0.5 gm. of phthalic acid anhydride and the various amounts of the N-substituted imides of fluorene succinic acid of example I. The resulting emulsions were applied at a rate of 25 gm. per square meter to a strong sodium Kraft paper having a weight of 85 gm./m. which was then dried at 140 C. to obtain a glossy film which adhered well to the paper and could be easily written upon. The reverse side of the coated-paper was then coated in a known manner with an adhesive consisting of 20'parts by weight of natural rubber, 5 parts by weight of zinc oxide, parts by weight each of polyterpene resin and colophonium, 5 parts by weight of oil soluble phenol resin and known stabilizers.

To test the adhesive strength of the coating of the invention in comparison with the adhesive, strips of adhesive papers 40 cm. long and 5 cm. wide were manually pressed onto the coated papers and the force required to remove the adhesive strip during one minute at an angle of 170 was determined. The adhesive strength in p and in of paper coated only with melamine-urea resin and etherified preliminary melamine condensate are shown in table I.

A mixture of 80 gm. of the melamine-urea resin of example Ill and gm. of the etherified condensate ofexample IV were admixed with 2.5 gm. and 5.0 gm., respectively, of N,N- dihexadecyl fluorenesuccinic acid amide. The resulting mixtures were diluted with 50 cc. of toluene and the emulsions were applied to sodium Kraft papers as in example II at a rate of 20 gm./m. The comparative decrease in adhesive strength was determined as in example V. The values were 450 p and 320 p for 2.5 gm. and 5.0 gm. respectively of the said amide.

EXAMPLE VII 5.2 gm. of fluorene succinic acid anhydride and 3.71 gm. of n-dodecylamine in 150 cc. of xylol were heated in a flask provided with a reflux condenser for 5 hours. Then, the solvent was distilled off and the residue was recrystallized from a mixture of xylol and toluol (1:1) to obtain N ,N -di-n-dodecyl fluorene-succinic acid diamide melting at 145 C.

Analysis C l-i N o z molecular weight =6 l 6.94 Calculated:% C 79.31 H 10.87 %N 4.95 Found: 79.80 10.64 4.54

The said diamide was sprinkled onto a strong sodium Kraft pager having a weight of gm./m. and was then melted at 5 C. After cooling, adhesive strips were pressed manually onto the treated paper and the force required to remove the adhesive strip was determined by ASTM D. 1000-65. The adhesive strength in p was 30 p compared to a strength of 80 p for untreated paper EXAMPLE VIll A cellophane strip was dipped into a benzene solution containing 10 percent of N-octadecyl fluorene-succinicimide and the strip was then dried. A 2.5 cm. wide adhesive tape was pressed onto the said treated cellophane strip. The force required to strip off the adhesive tape at an angle of 180 and at a stripping speed of 30 cmjmin. was determined. The relative humidity was 65 percent and the temperature was 20 C. during the test. The stripping force was between 500 and 550 p as compared to a stripping force of 800-900 p for untreated cellophane.

EXAMPLE lX N-octadecyl fluorene-succinicimide was sprinkled in a thin layer on heavy sodium Kraft paper weighing 80 g./m. and the paper was heated at 120 C. to melt the said product to form a thin film on the Kraft paper. Using the method in example Vlll, the stripping force was determined to be 60 p compared to a stripping force of 80 p for untreated Kraft paper.

Various modifications of the invention may be made without departing from the spirit or scope thereof and it is to be understood that the invention is to be limited only as defined in the appended claims.

We claim:

1. A coating composition for providing cellulose-containing materials with a low adhesion coating in which the coating agent is at least one compound selected from the group consisting of imides and diamides of fluorene succinic acid (9) having at least one nitrogen substituent selected from the group consisting of aliphatic and cycloaliphatic of five to 22 carbon atoms.

2. A coating composition of claim 1 wherein the coating agent is an imide of fluorene succinic acid (9) having on the nitrogen an aliphatic of tive to 22 carbon atoms.

3. A coating composition of claim 1 wherein the coating agent is a diamide of fluorene succinic acid (9) wherein the nitrogen substituents are aliphatic of five to 22 carbon atoms.

4. A cellulose containing base material coated with a composition of claim 1 at a rate of 10 to gm. of said coating agent per square meter of base material.

5. The base material of claim 4 containing 20 to 50 gm. of said coating agent per square meter of base material. 

2. A coating composition of claim 1 wherein the coating agent is an imide of fluorene succinic acid (9) having on the nitrogen an aliphatic of five to 22 carbon atoms.
 3. A coating composition of claim 1 wherein the coating agent is a diamide of fluorene succinic acid (9) wherein the nitrogen substituents are aliphatic of five to 22 carbon atoms.
 4. A cellulose containing base material coated with a composition of claim 1 at a rate of 10 to 100 gm. of said coating agent per square meter of base material.
 5. The base material of claim 4 containing 20 to 50 gm. of said coating agent per square meter of base material. 